A wide range of optical sensing applications are known. Commonly, a medium in an optical device has a property (e.g., refractive index) which is sensitive to an external parameter (e.g., temperature). Light propagating in the medium can experience a change in a detectable property (e.g., phase) which can be measured outside the optical device, sometimes at a considerable distance, to infer a value of the sensed parameter.
Some applications can be limited by performance, e.g. a sensed parameter cannot be measured with a desired resolution because of noise. Some applications can be limited by complexity, for example, a requirement for a high-power laser with its attendant power and cooling systems, or assorted auxiliary devices to compensate for various confounding effects both within an optical sensing apparatus (e.g., scattering) or due to external influences (e.g., mechanical vibration).
Accordingly, there remains ample opportunity for improvements in optical sensing.